1113

• UCREFRP Catalog Number: 1113
• Author: Tyus, H. M.
• Title: Acquisition of Habitat Preference Data By Radiotelemetry, ‎(Proceedings of a Workshop on the Development and Evaluation of Habitat Suitability Criteria)‎.
• USFW Year: 1986.
• USFW - Doc Type: \
• Copyright Material: NO

with fixed-wing aircraft. Water conductivities and temperatures during
tracking operations were obtained from the U.S. Geological Service for the
Jensen, Utah, gaging station.
Habitat preference information was obtained from monitoring locations of
Colorado squawfish in the field and measuring habitat parameters at these
sites (Tyus et al. 1984). The initial contact site was recorded and diel
studies were made in 1980 and 1981, using the following sampling design. Fish
were selected by tag number using a table of random digits. The day was
divided into three 8-hour periods, and one period was picked at random.
Beginning with the selected 8-hour period, each fish was observed in turn, for
three 8-hour periods, and i±s location was recorded every 15 minutes. After
the fish had been observed for three 8-hour periods, the fish with the nex*.
tag number was observed. Habitat data were also collected during daylight
hours from 1980-85, but these data were recorded from single daily contacts.
When a fish signal was detected by search receiver (SR) and whip antenna, its
approximate frequency was tuned by the tracking receiver (RF) using another
whip antenna. At this point, further monitoring was accomplished on the
nearest river bank using the RF and loop antenna. At ]east two lines of sight
were transected through the signal source to form two legs of a triangle.
These lines were made reference transections by using two stakes driven into
the shoreline about 10 m distant. These stakes were aligned with the signal
source to furnish a convenient sighting reference. The lines of sight
established by the stakes were then checked frequently to make sure the fish
location was the same.
If a radiotel~~metered fish remained in one location for 30 minutes, it
was assumed that this was preferred habitat. At that time, microhabitat
information was recorded by wading or by boat. In determining the exact
location of the fish, the observer lined up the stakes previously driven into
the shoreline, to arrive at the apex of the resulting triangle. Habitat data
taken at the signal source included general habitat and substrate type, water
depth, and velocity. General habitat types included:
Shorelines = shallow, low-velocity waters next to shore
Eddies = deep shoreline whirlpools with upstream velocity
Runs = channels with swift laminar flow
Backwaters = semi-isolated water bodies with no measurable velocity
Pools = deep, quiet portions of the stream
Water depth, velocity, and substrate measurements were taken only when
the fish moved to another location or at the end of the st::dy period, to
minimize disturbance to the fish. Water depth was recorded by direct measure-
ment with a wading rod, and water velocit;• was measured 0.6 the distance below
the water surface with a Marsh-McBirney current meter. Substrate type was
obtained by direct observation and by probing with a wading rod. Beginning in
1984, additional readings were taken 2 m inshore (shallow) and 2 m offshore
(deeper) of the fish location.
Data obtained from fish captured by electrofishing during 1980-81 were
used in comparisons with the 1980-81 radiotelemetry data. An attempt was made
to reduce bias in fish collections by using a standardized sampling program,
and rivers studied were divided into eight relatively homogeneous sections of
145